Site-preservation means taking measures to minimize the resorption of the alveolar ridge at the same time as the extraction or subsequently to provide sufficient bone volume and good bone quality for later implant restoration. There are many methods of site preservation, and anything that can slow down the resorption of the alveolar ridge can be considered as site preservation, for example, choosing the right time to extract the tooth to minimize the damage to the alveolar bone (minimally invasive extraction), timely soft tissue coverage of the wound for immediate implantation, and filling with bone or bone grafting materials. Among them, the method of filling the extraction site with bone or bone substitute material is the most studied method due to its simplicity and minimal trauma, and the abundance of material sources. The effect on the formation of new bone in the extraction socket: From the implantology point of view, the site preservation technique should not only effectively reduce the resorption of the remaining alveolar ridge and provide a suitable three-dimensional position for the implant placement, but also provide good bone quality for the implant placement. That is, there should be a sufficient amount of new bone formation in the extraction socket after the site preservation and it should be able to form a good osseointegration with the implant.